[petsc-users] Increasing norm with finer mesh

[Mark Adams]

As Matt said you should see the initial 2-norm residual asymptote to a
constant with scaling, but it will rise.

I prefer the max norm for this reason. You can use -ksp_monitor_max, but
this does compute an extra residual, apparently, but I don't understand why
it should ...

If this does not asymptotic to constant and your problem is linear, you
have a bug.

On Mon, Oct 1, 2018 at 6:31 PM Weizhuo Wang <weizhuo2 at illinois.edu> wrote:

> Hi!
>
> I'm recently trying out the example code provided with the KSP solver
> (ex12.c). I noticed that the mean norm of the grid increases as I use finer
> meshes. For example, the mean norm is 5.72e-8 at m=10 n=10. However at
> m=100, n=100, mean norm increases to 9.55e-6. This seems counter intuitive,
> since most of the time error should decreases when using finer grid. Am I
> doing this wrong?
>
> Thanks!
> --
> Wang Weizhuo
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20181002/7bf58b81/attachment.html>